Table aliasing

Earlier on we discussed the idea of assigning a column with an alias

e.g. SELECT 123 AS my_number replaces ?column? with my_number

The same logic can be applied to tables:

Take the Customers table:

SELECT customer_id, customer_name, date_joined
FROM "sequel-mart-schema"."Customers";

Because we have only been using one table we've not had to reference the table name in the SELECT. The above is implicitly:

SELECT "Customers".customer_id, "Customers".customer_name, "Customers".date_joined
FROM "sequel-mart-schema"."Customers";

Aliasing with AS...

When we start to join multiple tables, we should alias the table names.

Just like when we alias a column, the AS keyword can alias a table

The Customers table could be aliased as cu and be re-written as

SELECT cu.customer_id, cu.customer_name, cu.date_joined
FROM "sequel-mart-schema"."Customers" AS cu;

This is for the following reasons:

• It makes the SQL shorter and more concise
• It makes it easier to follow the path of table joins
• It helps the database engine to locate the data faster
• If the table name changes, we only have to change it in one place per query